The remote Debian host is missing a security-related update.
It was discovered that Avahi, an implementation of the zeroconf protocol, can be crashed remotely by a single UDP packet, which may result in a denial of service.
Upgrade the avahi packages. For the oldstable distribution (lenny), this problem has been fixed in version 0.6.23-3lenny3. For the stable distribution (squeeze), this problem has been fixed in version 0.6.27-2+squeeze1.